Amniotomy device and assembly

ABSTRACT

An amniotomy device includes a shaft having a rupture crown disposed along a distal end portion of the shaft. The rupture crown includes a distal end defined by at least two leading bite wings and a recess formed in the distal end of the rupture crown between the leading bite wings. The leading bite wings are configured to engage amniotic membrane when the shaft is rotated and rupture the amniotic membrane.

CROSS-REFERENCE TO RELATED APPLICATION

This Non-Provisional patent application is a Continuation-in-Part andclaims the benefit of the filing date of Non-Provisional patentapplication Ser. No. 12/126,143 filed May 23, 2008, entitled “AMNIOTOMYDEVICE,” which claimed the benefit of the filing date of U.S.Provisional Patent Application Ser. No. 60/981,292 filed Oct. 19, 2007,entitled “AMNIOTOMY DEVICE.”

BACKGROUND

The amniotic sac is a pair of membranes that enclose a developing embryoas it develops to a fetus. The amniotic sac includes an inner membranecalled the amnion that contains the amniotic fluid and the fetus, and anouter membrane called the chorion that contains the amnion and a portionof the placenta. Amniotomy is the artificial rupture of membranes (AROM)that is usefully employed to induce and/or accelerate labor.

U.S. Pat. No. 4,662,376 provides an amniotomy instrument that includes acurved tube having a handle and a suction piston movably mounted withinthe tube. The tube terminates in a bell-shaped structure at a distalend, and includes piercing pins mounted within the tube. The piercingpins are positioned such that they cannot contact the fetus even as theamniotic sac is drawn into the tube. The instrument is configured fortwo-hand operation by an attending physician, where the piston isretracted within the tube, and a portion of the amniotic sac is drawninto the distal end of the tube to be pierced by the piercing pins.

U.S. Pat. No. 5,968,055 provides another amniotomy instrument. Theinstrument includes a curved elongated shaft having a distal end, wherethe distal end includes a rounded structure curved over a sharp, pointedhook. During use, the attending physician positions an index fingeralong the rounded structure to guide the sharp pointed hook to theamniotic sac. When in position, the hook is engaged with the amnioticsac to perforate the membranes.

Although generally effective and useful, the known AROM devices are notsuited for access through a minimally dilated, relatively closed cervix.Improvements to the devices employed to perforate the amniotic sac wouldbe welcomed by obstetric physicians and their patients.

SUMMARY

One aspect provides an amniotomy device including a shaft having arupture crown disposed along a distal end portion of the shaft. Therupture crown includes a distal end defined by at least two leading bitewings and a recess formed in the distal end of the rupture crown betweenthe leading bite wings. The leading bite wings are configured to engageamniotic membrane when the shaft is rotated and rupture the amnioticmembrane.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the disclosure and are incorporated in as a part ofthis specification. The drawings illustrate example embodiments andtogether with the description serve to explain principles of theinvention. Other embodiments and many of the intended advantages of theembodiments will be readily appreciated as they become better understoodby reference to the following detailed description. The elements of thedrawings are not necessarily to scale relative to each other. Likereference numerals designate corresponding similar parts.

FIG. 1A is a front view of an amniotomy device and a macroscopic frontview of a crown of the amniotomy device according to one embodiment.

FIG. 1B is a top view of the crown shown in FIG. 1A.

FIG. 2A is a side view of a crown of an amniotomy device according toanother embodiment.

FIG. 2B is a side view of a crown of another amniotomy device accordingto one embodiment.

FIG. 2C is a perspective view of a crown of another amniotomy deviceaccording to one embodiment.

FIG. 3 is a side view of an amniotomy device including a generallyconical crown disposed at a distal end of the amniotomy device accordingto one embodiment.

FIG. 4 is a side view of an amniotomy device including a generallyconical crown disposed at a distal end of the amniotomy device accordingto another embodiment.

FIG. 5 is a side view of a substantially cylindrical crown disposed at adistal end of an amniotomy device according to another embodiment.

FIG. 6 is a side view of a spherically-shaped crown disposed at a distalend of an amniotomy device according to another embodiment.

FIG. 7 is a perspective view of a clay model of an amniotomy deviceaccording to one embodiment.

FIG. 8 is a cross-sectional illustration of a uterus containing anamniotic sac and an amniotomy device inserted through a cervix incontact with the amniotic sac according to one embodiment.

FIG. 9A is a side view of an amniotomy device including a crown and asleeve retracted to expose the crown according to one embodiment.

FIG. 9B is a side view of the amniotomy device shown in FIG. 9Aillustrating the sleeve deployed over the crown.

FIG. 10A is a side view of the amniotomy device shown in FIG. 9Aillustrating the sleeve and a cutting edge coupled to the sleeveaccording to one embodiment.

FIG. 10B is a side view of the amniotomy device shown in FIG. 10Aillustrating the sleeve deployed to a cutting position in which thecutting edge is protectively retained within the sleeve.

FIG. 11A is a top view of the crown of the amniotomy device shown inFIG. 9A.

FIG. 11B is a top view of the amniotomy device shown in FIG. 9Aincluding the crown and the sleeve disposed around the crown.

FIG. 12A is a side view of a cutting edge configured for attachment tothe sleeve shown in FIG. 10A according to one embodiment.

FIG. 12B is a side view of another cutting edge configured forattachment to the sleeve shown in FIG. 10A according to one embodiment.

FIG. 13 is an exploded side view of a protective sleeve that isconfigured to be slideably coupled to an amniotomy assembly according toone embodiment.

FIG. 14 is a cross-sectional view of the protective sleeve coupled to ashaft of the amniotomy assembly shown in FIG. 13.

FIG. 15 is a front view of the protective sleeve attached to theamniotomy assembly shown in FIG. 13.

FIG. 16A is a cross-sectional view of an amniotomy assembly including anadvancer attached to an amniotomy device that is insertable into aprotective sleeve according to one embodiment.

FIG. 16B is a cross-sectional view of the amniotomy assembly shown inFIG. 16A illustrating a rupture crown protectively disposed within theprotective sleeve.

FIG. 17 is a top view of the protective sleeve shown in FIG. 16A.

FIG. 18 is a bottom view of the protective sleeve shown in FIG. 16A.

FIGS. 19A-24 are perspective views of various embodiments of rupturecrowns of amniotomy devices.

DETAILED DESCRIPTION

In the following Detailed Description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. In this regard, directional terminology, such as “top,”“bottom,” “front,” “back,” “leading,” “trailing,” etc., is used withreference to the orientation of the Figure(s) being described. Becausecomponents of embodiments of the present invention can be positioned ina number of different orientations, the directional terminology is usedfor purposes of illustration and is in no way limiting. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope of thepresent invention. The following detailed description, therefore, is notto be taken in a limiting sense, and the scope of the present inventionis defined by the appended claims.

Embodiments provide an obstetrical instrument configured to ruptureamniotic membranes of a pregnant woman to release the amniotic fluidretained by the membranes, and thus to induce labor prematurely andfacilitate delivery and/or to reduce the internal pressure within theuterus.

FIG. 1A is a front view of an amniotomy device 50 and a macroscopicfront view of a crown 58 of the amniotomy device 50 according to oneembodiment. Amniotomy device 50 includes a shaft 52 defining a proximalend 54, a distal end 56 separated from proximal end 54, and a crown 58disposed on distal end 56. Crown 58 includes a first set of leading bitewings 60 formed on a distal surface of crown 58, a second set oftrailing bite wings 62 formed on a side surface of crown 58, and a thirdset of trailing bite wings 63 disposed between bite wings 62 andproximal end 54.

In one embodiment, shaft 52 is substantially linear and characterized byan absence of curvature along a longitudinal axis of shaft 52. Shaft 52is configured to access a minimally dilated and relatively closedcervix. The absence of curvature of shaft 52 enables shaft 52 todirectly approach the amniotic sac without unduly pressing against thetissue of the vaginal vault and/or the cervix during insertion and/oruse. Shaft 52 includes a textured and/or knurled surface adjacentproximal end 54 configured to facilitate rotation of shaft 52 duringuse.

In one embodiment, the first set or flight of leading bite wings 60 isconfigured to engage tissue of an amniotic sac when shaft 52 is rotatedin a first direction (e.g., clockwise). The uni-directional nature ofthe bite wings 60 is configured such that bite wings 60 do not engagethe tissue of the amniotic sac when shaft 52 is rotated in a seconddirection opposite the first direction (e.g., counter-clockwise).Leading bite wings 60 are suited for axial insertion through arelatively closed cervix with minimal or no local trauma to the cervicaltissue. Bite wings 60 are configured to not cut the amniotic sac tissueupon contact, but are rather configured to engage the tissue of the sac,wrapping the tissue around the crown 58 as shaft 52 is further rotated,until the tissue is drawn into contact with and ruptured by the secondset of trailing bite wings 62, as described further below. To this end,bite wings 60 provide one means for engaging/wrapping of the tissue ofthe amniotic sac about crown 58 when device 50 is rotated.

In one embodiment, second set of trailing bite wings 62 is configured torupture the amniotic sac as the amniotic sac is drawn down a side ofshaft 52 into contact with the second set of trailing bite wings 62. Inother words, leading bite wings 60 capture the tissue of the amnioticsac and pull the amniotic sac down into engagement with the trailingbite wings 62. Trailing bite wings 62 are configured to rupture theamniotic sac and release amniotic fluid contained therein to inducelabor and/or reduce the internal pressure within the uterus. Thus,trailing bite wings 62 provide one means of rupturing the amniotic sacwhen device 50 is rotated.

In one embodiment, leading bite wings 60 taper between an apex 64 at adistal end of device 50 down to trailing bite wings 62. In oneembodiment, trailing bite wings 62 include a plurality of raised pointsconfigured to rupture the amniotic sac. In another embodiment, secondset of trailing bite wings 62 is configured to more fully engage theamniotic sac and draw the amniotic sac down the side of shaft 52 intocontact with the third set of trailing bite wings 63. Leading bite wings60 capture the tissue of the amniotic sac, bite wings 62 pull theamniotic sac down into engagement with the trailing bite wings 63, andtrailing bite wings 63 are configured to rupture the amniotic sac andrelease amniotic fluid contained therein to induce labor and/or reducethe internal pressure within the uterus. In one embodiment, third set oftrailing bite wings 63 include raised rupture-points that are disposedsubstantially perpendicular to bite wings 62.

FIG. 1B is a top view of crown 58 according to one embodiment. Leadingbite wings 60 include a uni-directional flight of edges 70 configured toengage with the amniotic sac. In particular, flight edges 70 areconfigured to snag or engage the tissue of the amniotic sac when shaft52 (FIG. 1A) is rotated in the first direction (the direction of thearrow R). Additional rotation of shaft 52 in the direction of arrow Rwraps or transports the tissue of the amniotic sac from a distal end ofcrown 58 to a proximal end of crown 58. Flight edges 70 are configuredto not engage with the amniotic sac when the shaft 52 is rotated in thecounter-clockwise direction when the shaft is viewed from the proximalend 54 to the distal end 56.

In one embodiment, shaft 52 is substantially linear, and leading bitewings 60 are configured to not engage with tissue until shaft 52 isrotated, e.g., in a clockwise manner. In this regard, amniotomy device50 is configured to be inserted into the cervix and maintained at aparticular longitudinal position as it is rotated, and is thusparticularly well suited for rupturing membranes of the amniotic sacwhen the cervix is relatively closed. In contrast, the curved amniotomyinstruments known in the art are manipulated into and out of the cervix,and are likely to traumatize the walls of a closed cervix as theinstruments are maneuvered to rupture the membranes of the amniotic sac.The amniotomy device 50 described herein is configured to provideimproved access to a cervix that is dilated less than 2 cm whileminimizing the potential for traumatizing the cervical tissue.

In one embodiment, shaft 52 and crown 58 are fabricated from the samematerial such that the device 50 is suited for autoclaving, steamsterilization, ethylene oxide sterilization, and other forms of surgicalinstrument cleaning. In one embodiment, amniotomy device 50 isfabricated from stainless steel. In another embodiment, amniotomy device50 is fabricated from a radio opaque plastic suited for single usedisposal medical products.

FIG. 2A is a side view of a crown 98 of an amniotomy device according toanother embodiment. Crown 98 includes a leading bite wing surface 100,and a trailing bite wing surface 102. Similar to the amniotomy device 50described above, leading bite wing surface 100 is configured to engagewith the amniotic sac and draw tissue to trailing bite wing surface 102,and trailing bite wing surface 102 is configured to rupture the amnioticsac. In particular, trailing bite wing surface 102 includes a pluralityof cutting serrations 104 disposed along the surface 102 configured torupture the amniotic sac.

FIG. 2B is a side view of a crown 108 of an amniotomy device accordingto another embodiment. Crown 108 includes a leading bite wing surface110 configured to engage and draw amniotic sac tissue to a trailing bitewing surface 112, and trailing bite wing surface 112 is configured torupture the amniotic sac. In one embodiment, crown 108 includes a radialprominence 114 configured to provide a guiding surface for the finger ofa physician when approximating the amniotic sac.

FIG. 2C is a perspective view of another crown 118 of an amniotomydevice according to one embodiment. Crown 118 includes a leading bitewing surface 120 configured to engage and draw amniotic sac tissue to atrailing bite wing 122, and trailing bite wing 122 is configured torupture the amniotic sac. In one embodiment, the trailing bite wing 122includes a cutting edge circumscribed along a periphery of crown 118.

FIG. 3 is a side view of an amniotomy device 130 according to anotherembodiment. Amniotomy device 130 includes a shaft 132 and a generallyconical crown 138 coupled to a distal end 136 of shaft 132. Crown 138includes a leading bite wing surface 140 that tapers to a trailing bitewing surface 142, and a blunt distal end 146 that is configured toatraumatically contact sensitive cervical tissue. In one embodiment,trailing bite wing surface 142 defines a plurality of pyramidal-shapedcutting teeth projecting from a side surface of crown 138.

FIG. 4 is a side view of an amniotomy device 150 according to anotherembodiment. Amniotomy device 150 includes a shaft 152 and a crown 158disposed on a distal end 156 of shaft 152. Crown 158 is similar in shapeto the generally conical crown 138 (FIG. 3), but includes a greatermultiplicity of pin-shaped bite wings disposed on a trailing bite wingsurface 162. In one embodiment, crown 158 includes a leading bite wingsurface 160 that conically tapers to trailing bite wing surface 162.Similar to the embodiments described above, leading bite wing surface160 is configured to engage and pull tissue of the amniotic sac, andupon further rotation of shaft 152, to deliver the tissue to trailingbite wing surface 162. Trailing bite wing surface 162 is configured torupture the amniotic sac as shaft 152 is rotated.

FIG. 5 is a side view of an amniotomy device 170 according to anotherembodiment. Amniotomy device 170 includes a shaft 172 and a crown 178disposed on a distal end 176 of shaft 172. In one embodiment, crown 178is generally cylindrical in shape and includes a leading bite wingsurface 180, and a trailing bite wing surface 182 that is substantiallyorthogonal to leading bite wing surface 180. In one embodiment, aknurled surface 184 is provided at a distal end of shaft 172 adjacent tocrown 178 to provide an index location for a clinician's finger when theclinician approximates the amniotic sac prior to perforating the sac.

FIG. 6 is a perspective view of an amniotomy device 190 according toanother embodiment. Amniotomy device 190 includes a shaft 192 and acrown 198 disposed on a distal end 196 of shaft 192. Crown 198 includesa leading bite wing surface 200 configured to engage and draw amnioticsac tissue to a trailing bite wing surface 202, and trailing bite wingsurface 202 is configured to rupture the amniotic sac. In oneembodiment, the trailing bite wing surface 202 includes an edge 204configured to rupture the amniotic sac without cutting cervical tissue.

FIG. 7 is a perspective view of a clay model of an amniotomy crown 222according to one embodiment. Amniotomy crown 222 includes a bluntleading end 224, a first set of leading bite wings 226 formed on adistal surface 228 of crown 222, and a second set of trailing bite wings230 formed on a side surface 232 of crown 222.

FIG. 8 is a cross-sectional illustration of a uterus U containing anamniotic sac S and an amniotomy device 50 inserted through a cervix C incontact with the amniotic sac S according to one embodiment. Amnioticsac S is disposed within uterus U and includes the amnion and chorionlayers that retain the amniotic fluid A and the fetus. During pre-laborprior to the delivery of the fetus through the cervix C, a physician maydetermine that it is desirable to rupture the amniotic sac S to relievethe intrauterine pressure and initiate labor. To facilitate initiationof labor, the physician inserts amniotomy device 50 into the cervix Cuntil crown 58 contacts amniotic sac S. Blunt apex 64 (FIG. 1A) at adistal end of device 50 enables the easy insertion of device 50 into thecervix C while minimizing the possibility of undesirably tearingcervical tissue. In one embodiment, blunt apex 64 is sized to enable aphysician's finger to protectively cover at least a portion of theleading bite wings when inserting the rupture crown into a birth canal.That is to say, the diameter of the blunt distal end of the rupturecrown is sized so that the physician is able to cover the distal endwith the tip of a finger as the device is inserted into the cervix, thusminimizing the possibility of undesirably discomforting the patient. Forexample, the physician employs a finger to provide clearance between thecervix C and the device 50 to prevent unintentionally touching thecervix C with device 50.

By rotating amniotomy device 50 in the direction of the arrow R, leadingbite wings 60 (FIG. 1A) capture the tissue of the amniotic sac S andpull a portion of the sac S down into engagement with the trailing bitewings 62, 63 (FIG. 1A). Trailing bite wings 62 or 63 rupture theamniotic sac S and release amniotic fluid A contained in the sac S,thereby inducing labor and reducing the internal pressure within theuterus U. In this manner, the physician is able to rupture the sac Smembranes by sliding device 50 through the cervix C, followed by axialrotation of device 50.

Device 50 punctures the amniotic sac S via rotational motion. Incontrast, the known curved devices can potentially press against thesensitive tissue of the cervix C walls as the physician moves the curveddevice into and out of the cervix in an attempt to engage the cuttinghook or suction tube with the amniotic sac, a condition that isexacerbated when the cervical passage is relatively closed. Moreover,some known devices necessitate forcing the device axially into thecervix to hook or engage the tissue, which is a motion that couldpotentially unintentionally drive the device through the amniotic sac.

Other embodiments are provided below to protectively cover the cuttingedges of AROM devices when inserting the device into a birth canal.

FIGS. 9A and 9B are side views of an amniotomy device 250 including acrown 258 and a sleeve 260 retractable relative to crown 258 accordingto one embodiment. Amniotomy device 250 includes a shaft 252 defining aproximal end 254, a distal end 256 separated from proximal end 254,crown 258 disposed on distal end 256, and a sleeve 260 that isretractable relative to crown 258. In one embodiment, shaft 252 andcrown 258 are similar to shaft 52 and crown 58 described above, wherecrown 258 includes bite wings or other forms of a surface that isconfigured to engage tissue of the amniotic sac when shaft 252 isrotated. In one embodiment, sleeve 260 is configured to slide relativeto crown 258 and includes a first stowed position in which crown 258 isexposed for engagement with the amniotic sac, and a second deployed,cutting position in which sleeve 260 slides over crown 258 to pierce theamniotic sac.

For example, FIG. 9A is a side view of amniotomy device 250 showingsleeve 260 retracted to the first position in which crown 258 is exposedfor engagement with amniotic sac tissue. In one embodiment, about 1-2 cmof crown 258 is exposed when sleeve 260 is retracted. In otherembodiments, less than 1 cm or more than 2 cm of crown 258 is exposedwhen sleeve 260 is retracted. In a manner consistent with that describedabove in FIG. 8, shaft 252, when rotated, enables crown 258 to engageand grasp the amniotic sac S tissue.

FIG. 9B is a side view of amniotomy device 250 showing sleeve 260deployed to the second cutting position in which the sleeve 260 coverscrown 258. In one embodiment, sleeve 260 includes a flange 270 disposedon a proximal end 272. Flange 270 provides a grasping surface thatenables sleeve 260 to be engaged and slid distally relative to shaft 252(upward in the orientation of FIG. 9B). In one embodiment, flange 270 isergonomically formed to provide a pad suited for grasping by an indexfinger and a middle finger, for example, of a hand that engages theshaft 252. After engaging the tissue of amniotic sac S with crown 258,the clinician or physician slides sleeve 260 upward by guiding flange270 distally with pressure from a thumb or one or more fingers. In thismanner, sleeve 260 slides distally over crown 258 and a cutting surfaceinternal to sleeve 260, described below, is configured to pierce orsever the tissue of the amniotic sac S. Stops 278 are provided to limittravel of sleeve 260. A stop 279 is provided to ensure that a cuttingedge attached to sleeve 260 is not exposed when crown 258 is exposed.

FIG. 10A is an enlarged side view of amniotomy device 250 with sleeve260 retracted and crown 258 exposed. In one embodiment, shaft 252defines a channel 280 and sleeve 260 includes a cutting edge 282 that isconfigured to slide along channel 280. In one embodiment, channel 280extends along shaft 252 up to a point 284 that is offset from a top 286of crown 258. In this manner, cutting edge 282 is configured to slide upchannel 280 and yet not project beyond top 286 of crown 258, whichprotects the clinician, the mother, and the infant being delivered fromcutting edge 282.

In one embodiment, channel 280 includes a first stop 290 configured tolimit travel of cutting edge 282 to a point that does not project beyondthe top 286 of crown 258. In one embodiment, channel 280 defines asecond stop 292 configured to maintain sleeve 260 in a deployed positionsuch that crown 258 is exposed.

In one embodiment, sleeve 260 includes an upper stop 294 and a lowerstop 296. In one embodiment, stops 294, 296 include gaskets configuredto seal about a perimeter of shaft 252 and crown 258 such that cover 260encloses shaft 252 with a minimum amount of clearance.

Cutting edge 282 includes blades, hooks, serrated edges, or a sharppoint configured to rupture amniotic sac tissue when cutting edge 282 isengaged with the tissue.

FIG. 10B illustrates sleeve 260 moved upward relative to crown 258 in amanner that enables cutting edge 282 to pierce or cut into tissueengaged by crown 258. Sleeve 260 includes rigid materials configured toprotectively cover crown 258 and maintain cutting edge 282 withinchannel 280. Suitable materials for sleeve 260 include plastics andmetal. In one embodiment, sleeve 260 is fabricated from stainless steeland includes cutting edge 282 integrally formed and disposed on aninterior surface of sleeve 260.

FIG. 11A is a top view of crown 258. In one embodiment, shaft 252defines a pair of opposing channels 280 a, 280 b formed in a side wallof shaft 252. In one embodiment, channels 280 a, 280 b extend to adistal end 286 of shaft 252. In another embodiment, channels 280 a, 280b do not extend up to distal end 286 of shaft 252 and are offset adistance 284 away from distal end 286 (FIG. 10A).

FIG. 11B a top view of crown 258 and sleeve 260 disposed around aperimeter of crown 258. In one embodiment, sleeve 260 defines opposingcutting edges 282 a, 282 b that are configured to slide within opposingchannels 280 a, 280 b, respectively.

FIGS. 12A and 12B illustrate other embodiments of cutting edges. FIG.12A is a side view of a serrated cutting edge 298 extending from asupport 299 according to one embodiment. Cutting edge 298 includes aplurality of serrations that are configured to engage with the amnioticsac S to ensure that the sac is punctured when amniotomy device 250 isemployed. In one embodiment, cutting edge 298 is protectively recessedwithin sleeve 260 when device 250 is inserted into the vaginal introitusand is adapted to be deployed to extend from sleeve 260 in a mannerconfigured to puncture the amniotic sac S. Support 299 is configured toproperly position cutting edge 298 relative to the amniotic sac afterthe sac is engaged by crown 258 (FIG. 10A).

FIG. 12B is a side view of another cutting edge 300 according to oneembodiment. Cutting edge 300 includes a support 302. Support 302 isconfigured to engage with stop 290 (FIG. 10A) such that cutting edge 300is exposed relative to crown 258 (FIG. 10A). In this manner, after theamniotic sac S is engaged by crown 258, cutting edge 300 is properlypositioned to puncture the sac.

FIG. 13 is a partially exploded side view of an amniotomy assembly 400according to one embodiment. Amniotomy assembly 400 includes anamniotomy device 402 and a protective tubular sleeve 404 that isattachable to amniotomy device 402. In one embodiment, tubular sleeve404 is removable from amniotomy device 402 to enable cleaning of device402 and disposal/replacement of sleeve 404. In general, tubular sleeve404 slides along a distal portion of amniotomy device 402 to selectivelyexpose a cutting head provided on a distal end of amniotomy device 402.

In one embodiment, amniotomy device 402 includes a shaft 410, a rupturecrown 412 disposed at a distal end portion 414 of shaft 410, a channel416 formed in shaft 410 to extend between distal end portion 414 and amid-region 418 of shaft 410, and a relief slot 420 communicating withchannel 416.

In one embodiment, rupture crown 412 is similar to crown 58 (FIG. 1B)and includes a first set 430 of leading bite wings formed adjacent adistal end 432 of shaft 410 and a second set 434 of trailing bite wingsformed on a side of rupture crown 412 along a side of shaft 410 andadjacent to distal end portion 414. Amniotomy device 402 as describedabove is rotatable such that first set 430 of leading bite wings engagewith amniotic sac. Further rotation of shaft 410 transports tissue ofthe amniotic sac to the second set 434 of trailing bite wings, which areconfigured to rupture the amniotic sac.

Channel 416 extends along a portion of shaft 410. In one embodiment,channel 416 includes a longitudinal channel 440 that is parallel to alongitudinal axis of shaft 410, a distal section 442 communicating withlongitudinal channel 440, and a proximal section 444 also communicatingwith longitudinal channel 440. Channel 416 is formed in shaft 410 by asuitable process such as milling, molding, or other process configuredto form a relief in shaft 410. In one embodiment, distal section 442 andproximal section 444 are formed to be substantially normal to thelongitudinal axis of shaft 410 (and normal to longitudinal channel 440).

Tubular sleeve 404 is configured to be introduced over distal end 432 ofshaft 410 and slid along relief slot 420 until engaged with channel 416.When so assembled, tubular sleeve 404 is moveable relative to rupturecrown 412 between a first position in which rupture crown 412 isprotected and resides within tubular sleeve 404 and a second position inwhich rupture crown 412 extends out of tubular sleeve 404. A plunger 450is provided that deflects (e.g., up and down) to guide a structureformed inside of tubular sleeve 404 between distal section 442,longitudinal channel 440, and proximal section 444 of channel 416 astubular sleeve 404 moves along shaft 410.

Shaft 410 has a length of between about 14-16 cm. It is to be understoodthat tubular sleeve 404 retracts back onto mid-region 418 of shaft 410in a manner that fully exposes rupture crown 412, such that rupturecrown 412 is able to access the vagina without interference by tubularsleeve 404.

FIG. 14 is a cross-sectional view of amniotomy assembly 400 illustratingtubular sleeve 404 engaged with opposing channels 416 formed inlongitudinal channel 440. In one embodiment, tubular sleeve 404 includesa first boss 460 engaged with a first one of channels 416 and a secondboss 462 engaged with the opposing channel 416. Bosses 460, 462 areconfigured to ride within channel 416 to enable tubular sleeve 404 tomove within channels 416. In one embodiment, tubular sleeve 404 isdisposed over less than half of a length of shaft 410 and is configuredsuch that when bosses 460, 462 are engaged in proximal section 444 ofchannel 416, rupture crown 412 is exposed relative to tubular sleeve404. When bosses 460, 462 are engaged in distal section 442 of channel416, tubular sleeve 404 protectively shrouds or covers rupture crown412.

In one embodiment, bosses 460, 462 communicate with plunger 450. Whenplunger 450 is retracted rearward with a thumb, bosses 460, 462 movesinto proximal section 444 and tubular sleeve 404 is selectively retained(or locked) in the second rupture position. When plunger 450 isdepressed and pushed forward, bosses 460, 462 are directed out ofproximal section 444 into longitudinal section 440, thus moving tubularsleeve 404 over rupture crown 412.

FIG. 15 is a front view of distal end 432 of amniotomy assembly 400.Tubular sleeve 404 is disposed in close proximity around shaft 410 andmoveable to selectively expose bite wings 430.

FIG. 16A is a cross-sectional view of an amniotomy assembly 500according to another embodiment. Amniotomy assembly 500 includes anamniotomy device 502 axially disposed within a protective tubular sleeve504 and an advancer 506 coupled to amniotomy device 502. A portion ofadvancer 506 is inserted within tubular sleeve 504 and a second portionof advancer 506 is exposed outside of tubular sleeve 504 and configuredto be manipulated in presenting the cutting end portion of amniotomydevice 502 into and out of tubular sleeve 504.

Amniotomy device 502 is similar to those devices described above andincludes a rupture crown 510 having a first set 512 of leading bitewings formed on a distal end of rupture crown 510 and a second set 514of trailing bite wings formed on a side of rupture crown adjacent to adistal end portion 516 of shaft 518. Advancer 506 is coupled to shaft518 on a proximal end 520 opposite rupture crown 510.

In one embodiment, advancer 506 is provided as a part of shaft 518 andincludes a U-shaped advancer having a first leg 530 that is co-linearwith shaft 518, a second leg 532 parallel to first leg 530, and a base534 connected between proximal ends of first and second legs 530, 532.In one embodiment, first leg 530 includes a leading bead 536 and atrailing bead 538, both of which project toward second leg 532, and astopper 540 that projects a way from second leg 532. First and secondbeads 536, 538 are provided to selectively position or “lock” amniotomydevice 502 relative to sleeve 504 as device 502 is moved between a firstposition in which rupture crown 510 extends from tubular sleeve 504 anda second position in which rupture crown 510 is protectively stowedinside tubular sleeve 504. Stopper 540 is provided to limit axial travelof U-shaped advancer 506 as first leg 530 moves within sleeve 504.

In one embodiment, protective sleeve 504 includes an external fingerhold 540 that enables one-handed use of amniotomy assembly 500 by aphysician during an AROM procedure and pincers 542 that assist trailingbite wings 514 in rupturing the amniotic membranes. Pincers 542 aredisposed within sleeve 504 and configured to contact a portion ofrupture crown 510 to ensure that tissue entrained by crown 510 issheared (i.e., ruptured) when crown 510 is retracted into sleeve 504.

FIG. 16B is a cross-sectional view of amniotomy device 502 protectivelystowed within tubular sleeve 504. Advancer 506 has been retracted andtrailing bead 538 projects from a window formed in sleeve 504 to retaindevice 502 in the stowed position. Leading bead 536 is depressed againstan interior surface of tubular sleeve 504. In this manner, the sharpbite wings 512, 514 are protectively encased within tubular sleeve 504and configured for the safe insertion of assembly 500 into the cervixfor an AORM procedure.

After insertion of assembly 500 and immediately prior to membranerupture, second leg 532 is depressed against trailing bead 538, whichpresses bead 538 into window and enables advancer 506 to move forward toexpose rupture crown 510 beyond sleeve 504 (See FIG. 16A). To initiatemembrane rupture, assembly 500 is rotated to engage bite wings 512, 514with amniotic sac. Retraction of amniotomy device 502 into sleeve 504draws the amniotic sac across pincers 542 inside a distal end of sleeve504. Pincers 542 combine with bite wings 512, 514 to ensure thatamniotic sac is severed during the AORM procedure.

FIG. 17 is a top view of tubular sleeve 504. Tubular sleeve 504 definesan opening 570 sized to receive leading bead 536 (FIG. 16A), a window572 adjacent to proximal end 574, and an intermediate window 576 formedbetween opening 570 and first window 572. With reference to FIG. 16A,when advancer 506 is directed into tubular sleeve 504, leading bead 536projects through opening 570 and trailing bead 538 projects throughintermediate window 576. In this manner, beads 536, 538 “lock” advancer506 relative to sleeve 504 such that rupture crown 510 is exposed in acutting or AROM position.

With reference to FIG. 16B, when advancer 506 is retracted, trailingbead 538 is drawn into first window 572 and leading bead 536 is retainedinside tubular sleeve 504 between opening 570 and intermediate window576. In this manner, trailing bead 538 selectively locks into window 572to retain amniotomy device 502 in the stowed, protected position. Otherconfigurations for selectively locking or retaining device 502 relativeto sleeve 504 are also acceptable.

FIG. 18 is a bottom view of tubular sleeve 504. A slot 580 is formedadjacent to proximal end 574 and sized to receive stopper 540 (FIG.16A). Stopper 540 slides within slot 580 between a leading edge 582 thatlimits forward travel of advancer 506 and a trailing edge 584 thatlimits rearward travel of advancer 506.

In one embodiment, protective sleeve 504 presents a substantiallycircular transverse cross-sectional shape, although other shapes arealso acceptable. Assembly 500 is suited for one-handed use in firstinserting assembly 500 into the vagina adjacent to the cervix andthereafter advancing rupture crown 510 from sleeve 504 by manipulatingadvancer 506 with a thumb. Circular cross-sectional shape of protectivesleeve 504 enables assembly 500 to be comfortably rotated to engageamniotic sac with rupture crown 510. Thereafter, the physician places anindex finger proximal to finger hold 550 and retracts advancer 506 withthe thumb (or other fingers) to rupture the amniotic membranes.

During use, the amniotomy devices provided herein are configured toaccess a relatively closed endocervical canal and rupture an amnioticsac in an atraumatic manner that minimizes the force applied to theadjacent vaginal walls. In contrast, the known amniotomy devicesnecessitate “hooking” or engagement of the amniotic sac by directing thedevice against the vaginal walls, and prying the device further into thevaginal walls to rupture the amniotic membrane.

The amniotomy devices described herein provide for direct and atraumaticaccess into the relatively closed cervical canal when approximating theamniotic sac. Rotation of the amniotomy device in a first direction,clockwise for example, engages the tissue of the amniotic sac and drawsthe tissue in contact with a trailing bite wing surface. Upward movementof a sleeve coupled to a shaft of the amniotomy device directs a cuttingedge protectively recessed within the sleeve into contact with theamniotic sac, thus rupturing the membrane without uncomfortable andundesirable lateral force applied to the adjacent vaginal walls.

Embodiments described above provide an amniotomy device configured toaccess a relatively closed endocervical canal and rupture an amnioticsac in an atraumatic manner relative to the adjacent tissue. Theamniotomy devices described above provide for direct access into therelatively closed cervical canal when approximating the amniotic sac.Rotation of the amniotomy device in a first direction, clockwise forexample, engages the tissue of the amniotic sac and draws the tissue incontact with a trailing bite wing surface. Additional rotation of theshaft ruptures the amniotic sac. Rotating the amniotomy devices in asecond direction, counter-clockwise for example, results in the crown ofthe amniotomy device smoothly turning in contact with the amniotic sacand not engaging the tissue of the amniotic sac. In this regard, theamniotomy devices described above are configured to selectively engagewith the tissue of the amniotic sac to enable the controlled andselective rupturing of the tissue membranes via rotation of the shaft.

Embodiments described above provide an amniotomy device configured toaccess a relatively closed endocervical canal and rupture an amnioticsac in an atraumatic manner relative to the adjacent tissue. Theamniotomy devices provide for direct access into the relatively closedcervical canal when approximating the amniotic sac. Rotation of theamniotomy device in a first direction, clockwise for example, engagesthe tissue of the amniotic sac and draws the tissue in contact with atrailing bite wing surface. Upward movement of a sleeve coupled to ashaft of the amniotomy device directs a cutting edge protectivelyrecessed within the sleeve into contact with the amniotic sac, thusrupturing the membrane.

It is to be understood that the features of the various exemplaryembodiments described herein may be combined with each other, unlessspecifically noted otherwise.

By convention, “end” means the endmost location (the very end) of anobject, and “end portion” means a segment length extending a distanceaway from the end of the object. Thus, “distal end” means the very endof an object that is directed away from a user of the object, and“proximal end” means the very end of an object that is nearest the userof the object.

FIGS. 19-24 are perspective views of various embodiments of rupturecrowns of amniotomy devices.

FIG. 19A is a perspective view of an amniotomy device 600 according toone embodiment. Amniotomy device 600 includes a shaft 602 (only aportion of which is illustrated) having a distal end portion 604 and arupture crown 606 disposed along distal end portion 604. In oneembodiment, rupture crown 606 includes a distal end 608 defined by afirst leading bite wing 610 and a second leading bite wing 612 and has arecess 614 formed in distal end 608 between bite wings 610, 612. Theleading bite wings 610, 612 are configured to engage amniotic membranewhen shaft 602 is rotated and rupture the amniotic membrane.

Shaft 602 is similar to shaft 252 (FIGS. 10A and 10B) described aboveand is suitable for disposing within a sleeve such as sleeve 260 (FIG.10A). In one embodiment, shaft 602 and rupture crown 606 havesubstantially the same diameter. Alternatively, shaft 602 has a diameterthat is smaller than a diameter of rupture crown 606, in which caserupture crown 606 extends over a footprint of shaft 602.

In one embodiment, rupture crown 606 is formed as a circular cylindersuch that a lateral cross-section of rupture crown 606 provides asubstantially circular perimeter. In one embodiment, bite wing 610terminates at a pointed edge 616 that is formed as a cusp-like cuttingshape between surface 618 and surface 620. Pointed edge 616 is formedwithin a periphery of the circular rupture crown 606 such that theoutermost surface of rupture crown 606 is defined by exterior surface622 of bite wing 610. Consequently, pointed edge 616 of bite wing 610 isexposed on distal end 608 and does not extend beyond exterior surface622, which configures rupture crown 606 to effectively engage with theamniotic sac while minimizing the likelihood of tissue discomfort wheninserting amniotomy device 600 into cervix C (FIG. 8).

In one embodiment, bite wings 610, 612 are provided as pointedprojections that extend around distal end 608 of rupture crown 606 in acircular arc. In other words, bite wings 610, 612 have a circularboundary provided by exterior surface 622 of rupture crown 606. Recess614 is an annular recess formed in distal end 608 to extend a distanceinto distal end portion 604 of rupture crown 606. In one embodiment,surface 618 is formed by opening a slot 624 into exterior surface 622 ofrupture crown 606, such that slot 624 communicates with annular recess614.

When amniotomy device 600 is employed to rupture an amniotic sac,rupture crown 606 is introduced into the cervix C (FIG. 8) into contactwith amniotic sac S, shaft 602 is rotated, and opposing bite wings 610,612 grasp the amniotic membrane. Recess 614 provides clearance toreceive the amniotic membrane that is wrapped onto and over rupturecrown 606. The amniotic sac may be ruptured by a slight tug delivered toamniotomy device 600 or by further rotating amniotomy device 600 bytwisting shaft 602.

FIG. 19B is a perspective view of another embodiment of an amniotomydevice 600B. Amniotomy device 600B is similar to device 600 (FIG. 19A)and includes a distal end portion 604B provided with and a rupture crown606B. In one embodiment, rupture crown 606B includes a distal end 608Bdefined by a first leading bite wing 610B and a second leading bite wing612B, where one or both of the leading bite wings 610B, 612B are formedto include a serrated leading edge defined by multiple smaller bitewings 613 or bite teeth 613. Bite wings 610, 612 and bite teeth 613combine to engage amniotic membrane when shaft 602. The positiveengagement of the amniotic sac by the multiplicity of leading-end bitewings results in consistent and controlled rupture of the amnioticmembrane.

FIG. 20 is a perspective view of another embodiment of an amniotomydevice 650. Amniotomy device 650 includes a shaft 652 providing a distalend portion 654, and a rupture crown 656 disposed along distal endportion 654 and defining a distal end 658. In one embodiment, distal end658 of rupture crown 656 is defined by a first leading bite wing 660 anda second leading bite wing 662 disposed on an opposing side of a recess664 formed in distal end 658 of rupture crown 656.

In one embodiment, a lateral cross-section of rupture crown 656 issubstantially circular, although embodiments of rupture crown 656 caninclude a conical shape. An exterior surface 670 of rupture crown 656 isformed to include one or more trailing bite wings 672 and/or 674configured to wrap amniotic membrane onto the rupture crown. Forexample, in one embodiment exterior surface 670 is formed to include agroove 672 that provides a trailing bite wing configured to grasp andengage with amniotic membrane that is pulled down over rupture crown656. In one embodiment, groove 672 is a helical groove and is configuredto auger or engage amniotic membrane when shaft 652 is rotated. In oneembodiment, the trailing bite wing of rupture crown 656 is provided as aprong 674 that projects from exterior surface 670. Prong 674 isconfigured to capture amniotic membrane as shaft 652 is rotated, andfurther provides a mechanism for tearing the amniotic membrane whenshaft 652 is pulled or rotated.

It is to be understood that one or both of bite wings 660, 662 could bemodified to include a multiplicity of smaller leading bite wing teeth,similar to teeth 613 illustrated in FIG. 19B.

FIG. 21 is a perspective view of another embodiment of an amniotomydevice 700. Amniotomy device 700 includes a shaft 702 providing a distalend portion 704 and a rupture crown 706 disposed along distal endportion 704. Rupture crown 706 includes a distal end 708 defined bymultiple leading bite wings 710, 712, 713 disposed around a recess 714formed in distal end 708. In one embodiment, recess 714 is formed as asemi-spherical depression in distal end 708.

In one embodiment, a lateral cross-section of rupture crown 706 isgenerally circular, and each of the leading bite wings 710, 712, 713curve around an exterior surface of rupture crown 706 such that aportion of each bite wing is formed in a circular arc.

In one embodiment, an exterior surface 720 of rupture crown 706 isfabricated to include trailing bite wings 722. For example, in oneembodiment exterior surface 720 is fabricated to include multiplegrooves 722 that extend along a portion of the length of distal endportion 704 to provide trailing bite wings configured to engage amnioticmembrane as shaft 702 is rotated.

Each of the leading bite wings 710, 712, 713 terminate in a point thatis disposed at distal end 708 of rupture crown 706. The points areconfigured to minimize discomfort to the patient since the bite wings710, 712, 713 fall along a circular arc on the perimeter of the rupturecrown 706 in a manner that prevents the points from projecting beyondcrown 706. When rupture crown 706 is rotated by rotating shaft 702, bitewings 710, 712, 713 entrain or dig into the amniotic membrane and pullit over rupture crown 706. Subsequent twisting of shaft 702 augers theamniotic membrane over rupture crown 706 where trailing bite wings 722further engage with the amniotic membrane. In this manner, rotatingshaft 702 twists the amniotic membrane over rupture crown 706 tofacilitate a controlled rupturing of the amniotic sac.

FIG. 22 is a perspective view of another embodiment of an amniotomydevice 750. Amniotomy device 750 includes a shaft 752 providing a distalend portion 754 and a rupture crown 756 formed along distal end portion754 between a distal end 758 and a proximal end 759. In one embodiment,distal end 758 is defined by leading bite wings 760, 762 that are formedon a periphery of a recess 764. Recess 764 is formed in distal end 758.Proximal end 759 of rupture crown 756 is defined by a plurality oftrailing bite wings 766, 768. Rupture crown 756 thus includes leadingbite wings 760, 762 formed at distal end 758 and trailing bite wings766, 768 formed at proximal end 759.

In on embodiment, a lateral cross-section of rupture crown 756 iscircular and exterior surface 770 tapers between distal end 758 andproximal end 759. Each leading bite wing 760, 762 is formed along an arcon an exterior surface 770 of rupture crown 756. The bite wings 760, 762are thus protectively “tucked inside” a periphery of the circularexterior of rupture crown 756. In one embodiment, grooves 772 are formedbetween distal end 758 and proximal end 759, where the grooves 772 andthe bite wings 760, 762, 766, 768 combine to grasp and positively engageamniotic membrane when shaft 752 is rotated.

FIG. 23 is a perspective view of another embodiment of an amniotomydevice 800. Amniotomy device 800 includes a shaft 802 having a distalend portion 804 and a rupture crown 806 disposed along distal endportion 804. In one embodiment, rupture crown 806 includes a distal face808, multiple prongs 810 extending axially relative to shaft 802 fromdistal face 808, and multiple axial recesses 812 formed in distal face808. Prongs 810 are generally disposed between adjacent axial recesses812 and extend from distal face 808 to define a distal end 814 ofrupture crown 806. In one embodiment, axial recesses 812 are formed inan exterior surface 816 of rupture crown 806 and extend from distal face808 along a portion of distal end portion 804. In this manner, anexposed edge 818 is formed relative to each of the axial recesses 812,and the edges 818 provide a trailing bite wing configured to engageamniotic membrane.

While four prongs 810 and four axial recesses 812 are illustrated, it isto be understood that a different number (more or less) of prongs andrecesses could be formed on rupture crown 806.

When shaft 802 is rotated, prongs 810 grasp amniotic membrane and drawthe amniotic membrane between prongs 810 and into recesses 812. Thispositive engagement of rupture crown 806 with amniotic membrane providesthe attending physician improved control in rupturing the amniotic sacwhen compared to conventional amniotic rupturing devices.

FIG. 24 is a perspective view of another embodiment of an amniotomydevice 850. Amniotomy device 850 includes a shaft 852 that provides adistal end portion 854 and a rupture crown 856 disposed along distal endportion 854. Rupture crown 856 extends between a distal end 858 and aproximal end 859. Leading bite wings 860, 862 are formed on distal end858 around a periphery of a recess 864 formed in distal end 858. In oneembodiment, proximal end 859 is defined by trailing bite wings 866, 868.

In one embodiment, an exterior surface 870 of rupture crown 856 definesa circle in lateral cross-section and includes one or more grooves 872formed and extending between distal end 858 and proximal end 859.Exterior surface 870 generally tapers between distal end 858 andproximal end 859, although non-tapered (e.g., cylindrical) forms ofexterior surface 870 are also acceptable. In on embodiment, groove 872is an auger-style or helical-style groove configured to capture and/orengage with amniotic membrane of an amniotic sac.

In one embodiment, multiple prongs 874 are formed to extend fromexterior surface 870 of rupture crown 856. In one embodiment, prongs 874extend normal from exterior surface 870 and include a first set ofprongs disposed in a column on a first side of groove 872 and a secondset of prongs disposed in a column on a second side of groove 872. It isdesirable to stagger the first set of prongs relative to the second setof prongs to ensure that the amniotic membrane captured by rupture crown856 is securely grasped, which prevents the amniotic membrane fromundesirably disengaging with rupture crown 856.

It is to be understood that one or both of bite wings 860, 862 could bemodified to include a multiplicity of smaller leading bite wing teeth,similar to teeth 613 illustrated in FIG. 19B.

In one embodiment, the length of the distal end portion of theabove-described amniotomy devices illustrated in FIGS. 19-24 is betweenapproximately 0.75-2 inches, and preferably the length of the distal endportion of the amniotomy devices is between about 1-1.5 inches. Thediameter of the rupture crown of the amniotomy devices illustrated inFIGS. 19-24 is between approximately 2-10 millimeters, and preferablythe diameter of the rupture crowns of the amniotomy devices is betweenabout 3-6 millimeters.

In one embodiment, the above-described amniotomy devices illustrated inFIGS. 19-24 are formed from a polymer, for example in a molding processor an extrusion process or other suitable plastic forming process.Suitable polymers include polyolefin, polyamide, or thermoplastics ingeneral or thermosetting resins.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificamniotomy devices discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

1. An amniotomy device comprising: a shaft comprising a rupture crowndisposed along a distal end portion of the shaft, the rupture crowncomprising a distal end defined by at least two leading bite wings and arecess formed in the distal end of the rupture crown between the leadingbite wings, wherein the rupture crown is structurally configured to beatraumatically inserted into a cervical canal; wherein the leading bitewings are structurally configured to atraumatically engage an amnioticmembrane when the shaft is rotated.
 2. The amniotomy device of claim 1,wherein a lateral cross-section of the rupture crown is substantiallycircular.
 3. The amniotomy device of claim 1, further comprising: atleast one trailing bite wing formed on a side of the rupture crown;wherein the trailing bite wing is configured to wrap the amnioticmembrane onto the rupture crown.
 4. The amniotomy device of claim 3,wherein the trailing bite wing comprises a groove formed in the rupturecrown.
 5. The amniotomy device of claim 4, wherein the groove comprisesan auger defined by a helical groove formed in a surface of the rupturecrown.
 6. The amniotomy device of claim 3, wherein the trailing bitewing comprises at least one prong projecting from a side surface of therupture crown.
 7. The amniotomy device of claim 1, wherein the leadingbite wings comprise a first pointed projection separated from a secondpointed projection by the recess, each pointed projection comprising anexterior surface of the rupture crown and curved to extend around aportion of the rupture crown in a circular arc.
 8. The amniotomy deviceof claim 7, wherein the first and second pointed projections extendaround the distal end of the rupture crown in a circular arc such thatthe recess comprises an annular recess.
 9. The amniotomy device of claim7, wherein at least one of the leading bite wings comprise a serratedleading edge comprising a multiplicity of teeth.
 10. The amniotomydevice of claim 1, wherein the distal end of the rupture crown comprisesa plurality of prongs extending from the rupture crown and axiallyaligned with the shaft, and the recess comprises a plurality ofrecesses, each recess disposed between two adjacent prongs.
 11. Theamniotomy device of claim 1, wherein the rupture crown comprises acylinder and the leading bite wings comprise at least four radiallyextending bite wings, each bite wing comprising an exterior portion thatdefines a circular arc, the exterior portion of each bite wingterminating in a point.
 12. The amniotomy device of claim 1, furthercomprising: a tubular sleeve disposed over at least a portion of theshaft and selectively lockable to the shaft; wherein the tubular sleeveis movable relative to the rupture crown between a first position inwhich the rupture crown resides within the tubular sleeve and a secondposition in which the rupture crown extends from the tubular sleeve. 13.An amniotomy device comprising: a shaft comprising a rupture crowndisposed along a distal end portion of the shaft, the rupture crowncomprising a distal end, a recess formed in the distal end, and a pairof bite wings curved in a circular arc along an exterior boundary of therupture crown, wherein the rupture crown is structurally configured tobe atraumatically inserted into a cervical canal; wherein the pair ofbite wings are structurally configured to atraumatically grasp anamniotic membrane when the shaft is rotated.
 14. The amniotomy device ofclaim 13, wherein each bite wing comprises a point formed between thedistal end of the rupture crown and a slot formed in an exterior side ofthe rupture crown that communicates with the recess.
 15. The amniotomydevice of claim 14, wherein the distal end of the rupture crown isdefined by the point of each bite wing.
 16. The amniotomy device ofclaim 14, further comprising: at least one trailing bite wing extendingfrom the exterior side of the rupture crown.
 17. An amniotomy devicecomprising: a shaft comprising a rupture crown disposed along a distalend portion of the shaft, the rupture crown comprising a distal face, aplurality of prongs extending axially relative to the shaft from thedistal face, and a plurality of axial recesses formed in the distal faceof the rupture crown, each of the plurality of prongs disposed betweentwo adjacent axial recesses, wherein the rupture crown is structurallyconfigured to be atraumatically inserted into a cervical canal; whereinthe plurality of prongs are structurally configured to atraumaticallygrasp an amniotic membrane when the shaft is rotated.
 18. The amniotomydevice of claim 17, wherein each axial recess formed in the distal faceof the rupture crown is open to an exterior surface of the rupture crownalong an axial edge.
 19. The amniotomy device of claim 18, wherein eachaxial edge of each axial recess formed in the exterior surface of therupture crown comprises a trailing bite wing edge configured to engagethe amniotic membrane.